The present invention relates to an improved process for producing aromatic-containing silicon compounds and more particularly the present invention relates to producing alkoxy or chloro functional silphenylene compounds.
Grignard reagents are well known. Generally such reagents comprise a compound of the formula R"MgX where R" is a hydrocarbon radical and X is chloro, iodo or bromo. As is well known in the presence of ether solvents such compounds will react with other halocarbon compounds to add a hydrocarbon group on to the R" moiety. In a successful variation of such a reaction, there have been carried out reactions comprising reacting chlorobenzene in the presence of molar amounts of magnesium with chloro silanes to add on to the silane molecule the phenyl group of the chlorobenzene. Examples of such reactions are for instance those disclosed below: EQU .phi.Cl + Mg + .phi.SiCl.sub.3 .fwdarw..phi..sub.x SiCl.sub.4-x (x = 2,3,4) (a) EQU .phi.Cl + Mg + CH.sub.3 SiCl.sub.3 .fwdarw..phi..sub.y CH.sub.3 SiCl.sub.3-y (y = 1,2,3) (b)
In the above reactions .phi. is phenyl. Although such reactions were attempted to a certain extent successfully in the past it was found that the yield were not as much as would be desired and usually require the presence of an ether solvent in copious amounts making such reactions hazardous, as well as expensive. Accordingly, it was highly desirable to be able to carry out the above reactions without the presence of a hazardous type of solvent and with as little an amount of solvent as possible so as to save in cost. Further, such reactions were particularly desirable to produce a silphenylene compound by reacting dichlorobenzene with a chloro silane so as to append silane groups to the divalent phenylene radical and produce a silphenylene compound. However, with the exception of the use of dibromobenzene as the reactant, it was found that such reactions would not result in a good yield of the desired silphenylene compound. It was found that when dichlorobenzene was utilized as the reactant that the second chlorine atom was not inclined to be substituted using the foregoing modified Grignard reactions.
Accordingly, various modified processes were utilized to prepare silphenylene compounds. Such modification of the Grignard reaction to produce silphenylene compounds is for instance to be found in Merker U.S. Pat. 3,202,634. As disclosed in Column 6 of the patent, the silphenylene compounds were obtained by the reaction of a dibromo or dichloro benzene with magnesium and a hydro silane to produce a hydrogenated silphenylene compound which in turn was converted to the silphenylene diol by reacting the silphenylene compound with a sodium hydroxide or potassium hydroxide in a mixture of alcohol and water. The resulting silphenylene diol could then be utilized as disclosed in Merker to produce block copolymers. However, in the initial reaction of producing the hydrogen containing silphenylene compound, the yields were not high and still necessitated the use of copious amounts of solvent; one specific such solvent being tetrahydrofuran. A more direct process in the production of silphenylene compounds is to be found in Omietanski U.S. Pat. No. 3,053,872. This patent discloses that in the production of silphenylene compounds of Formula 1 of the Patent X.sub.m 'SiR.sub.4-m.sup.3 could be reacted with dibromobenzene with molar amounts of magnesium so as to substitute the silane for the bromine atoms in the dibromobenzene. As defined in the Omietanski Patent R.sup.3 stands for a monovalent hydrocarbon radical, while X' stands for halogen, alkoxy, phenoxy or an alkyl-substituted phenoxy radical and m is an integer having a value of from 1 to 3. Omietanski found that the modified Grignard reaction which is disclosed in the patent utilizing a dibromobenzene could be improved upon in that dichlorobenzene could be utilized as a reactant. Omietanski disclosed that such a process was possible over what had been done in the prior art in that a process where dichlorobenzene was reacted with molar amounts of magnesium and dimethyldichlorosilane to produce silphenylene compounds could be carried out by utilizing as a solvent copious amounts of tetrahydrofuran. Accordingly, Omietanski found that the desired chloro or alkoxy silphenylene compound could be obtained in good yields by the utilization of such a solvent. For instance in Example 2 Omietanski discloses the utilization of 500 milliliters of dry tetrahydrofuran per 147 grams of dichlorobenzene in his process. In Example 3 there is disclosed the use of 2000 milliliters of tetrahydrofuran and 441 grams of dichlorobenzene and in Example 5 the use of 750 milliliters of tetrahydrofuran and 147 grams of dichlorobenzene. Omietanski envisioned utilizing large amounts of tetrahydrofuran in his process to obtain the substitution of the chlorine groups in the para-dichlorobenzene in the modified Grignard reaction. While such was an innovation over the prior art, such a process has the disadvantage which includes also the process of the Merker Patent that tetrahydrofuran has to be utilized in copious amounts as a solvent. Note the discussion in Column 2 beginning with Line 17 of the Omietanski patent.
Accordingly, such use of copious amount of tetrahydrofuran has the disadvantage of increasing the cost of the process by utilizing as a solvent a material which is not one of the common solvents. Accordingly, it was highly desirable to find a process in which the silphenylene compounds could be obtained, without the use of a solvent or in the presence of as little amount of solvent as possible.
Accordingly, it was highly unexpected to find in view of Omietanski that the foregoing modified Grignard reaction could be carried out with promoter amounts of tetrahydrofuran, that is quantities of from 0.5 moles of tetrahydrofuran to up to 1 mole of tetrahydrofuran per mole of dichlorobenzene.
Accordingly, it is one object of the present invention to provide for an improved process for producing phenyl chlorosilanes utilizing a modified Grignard reaction with promoter amounts of tetrahydrofuran.
It is an additional object of the present invention to provide a process of producing silphenylene compounds utilizing promoter amounts of tetrahydrofuran.
It is a further object of the present invention to provide an improved process for producing phenyl chlorosilanes wihtout a solvent and in the presence of promoter amounts of tetrahydrofuran.
It is yet an additional object of the present invention to provide an improved process for producing silphenylene compounds by reacting a chlorosilane or an alkoxylated silane with dichlorobenzene in the absence of a solvent and in the presence of promoter amounts of tetrahydrofuran. These and other objects of the present invention are accomplished by means of the disclosure set forth hereinbelow.